Defense Secretary Ash Carter has tapped a one-star Marine Corps general to be his senior military adviser, replacing the Army three-star who was fired last month, a defense official said.

Carter selected Brig. Gen. Eric M. Smith, currently commander of U.S. Marine Corps Forces South, according to a defense official who spoke on condition of anonymity because the appointment has not been publicly announced.

The secretary's senior military adviser is a highly influential military officer who provides the Defense Department's civilian leader with key military advice on all matters of policy and strategy.

Carter abruptly fired Army Lt. Gen. Ronald A. Lewis on Nov. 13 and asked the Pentagon's inspector general to investigate allegations of misconduct involving Lewis, defense officials said. Officials declined to identify nature of the allegations.

Carter previously worked with Smith when Carter was the Defense Department's deputy secretary of defense in 2013 and Smith was senior military adviser to that position.

Smith is a former foreign-area officer who speaks Spanish and served in Venezuela from 2001 to 2003. From 2003 until 2006, he deployed twice to Iraq while serving in the 1st Marine Division.